E-tail sites choked by holiday frenzy?

Above average demand on e-commerce sites may put a damper on online holiday sales.

Internet performance company Keynote Systems said data late Monday indicated that top online retail sites may be inadvertently turning away customers because of higher-than-expected demand.

According to the company's E-Commerce Web Transaction Performance Index, the time it takes to complete a sale on a site has increased to a daily average of 21 seconds from the typical 14 seconds. Reliability also is down to 80 percent from an average of 97 percent.

"One out of five people weren't able to make purchases online," said Roopak Patel, a senior Internet analyst for Keynote's public services division.

Patel said the slowdown started Monday morning around 7 a.m. PT and has continued throughout the day.

Keynote has not noticed any major changes to overall Internet performance.

Patel said consumers may have waited to get to work, where they have higher-speed Internet access, to make gift purchases.

Retailers are expecting this holiday season to be a big one for online sales, and most early indicators have been positive.

Web statistician ComScore Networks said online spending between Nov. 1 and Nov. 26 was up 23 percent compared with the same period last year.

Online spending in 2004 through the day after Thanksgiving--also known as "Black Friday" in the retail industry because heavy sales have pushed retailers into profitability for the year--totaled $5.7 billion, compared with $4.6 billion in 2003. Spending on Black Friday didn't disappoint; U.S. consumers accounted for $250 million in online sales, a 41 percent increase over the $178 million reported for 2003.

A spokeswoman from Amazon.com said she wasn't aware of any slowdown on the company's site, adding that Amazon doesn't release such information. A representative from Best Buy similarly said the company doesn't release daily performance numbers but it has been making efforts to improve its Web site.